I believe that the correct answer is D because it is already stated once that they need the sirens so it is giving us a fact that has already been stated.
Explanation:
child may argue for a dog. The parents remind the child his sister is allergic to dogs. The boy uses the counterargument that she has been around some dogs without any problems. He is ready for each argument against the dog, perhaps stating there are breeds of dogs that are hypoallergenic.
